Life Cycle Assessment of Networked Geothermal Systems: A Path to Sustainable Urban Energy

Abstract

This study presents results of life cycle assessment (LCA) of networked geothermal systems (Net-Geos) in urban environments, focusing on environmental impacts. Net-Geos connects multiple building types—including single-family, multi-family, and commercial—via a shared underground loop of ambient-temperature water, delivering heating and cooling through ground-source heat pumps (GSHPs). By enabling heat exchange between buildings, Net-Geos enhance energy efficiency, reduce fossil fuel reliance, and lower greenhouse gas (GHG) emissions.Based on the Massachusetts pilot project, this study initially focuses on five single-family homes in Lowell, MA, as part of a broader Net-Geo system serving 13 buildings with 44 boreholes. To build the life cycle inventory, data were collected from design documents provided by National Grid, supplemented by LCA databases and literature for materials, manufacturing, and installation processes.A static LCA approach was applied to compare Net-Geos with conventional heating, ventilation, and air conditioning (HVAC) systems powered by natural gas and electricity over a 25-year lifecycle. Preliminary results indicate that Net-Geos achieve approximately 26% lower GHG emissions, largely due to a 72% reduction in operational emissions from GSHPs compared to traditional systems. These findings underscore Net-Geos’ environmental benefits and potential for sustainable urban energy solutions.Future work will expand this model to evaluate multi-family and commercial buildings within the Net-Geo design and incorporate life cycle cost analysis. By supporting SDGs 7, 9, 11, and 13, this research provides a framework to assess Net-Geos’ sustainability across diverse urban settings, advancing insights for broader adoption and urban resilience.